I'm over 60 and have been using TeX since '85. Same manual after all these years... I still seem to be able to learn new stuff, though it's not always clear it's worth the bother.

So I'm guessing you were 28-38 when you learned TeX, rather than 60+.

If you were over 60 in 1985 and are still posting to HN, that would be really cool.

Indeed, I was 30 and my brain was still plastic. Really, the only notable thing from my post was the fact I'm still using the same Latex manual after all these years. Kinda ragged now, but still useful.

I will be 60 in a few months. I am a math[s] teacher. I have been using TeX since late 80s/early 90s when I started using small computers.

why would someone with 40+ years of math experience have such a hard time learning a new notation?

I don't think their assertion is that someone with 40+ years of math experience would have difficulty learning new notation, it's that LaTeX is composed of a lot more than straightfoward notation. LaTeX can get pretty complicated pretty quickly. While it's basic math notation is quite fantastic, it's the basic document formatting that I think would give most people trouble when learning.

Because the error messages from latex are truly awful, even just putting an underscore or less than in plain text is painful.

Assuming they have something that already works for them, lack of motivation.

Because knowledge about maths is independent of computer and programming literacy.

if we use a liberal definition of "computer and programming literacy", then it's just as much a requisite for math as it is TeX.

if we use a conservative definition of "computer and programming literacy", then it's not a requisite for either.

markup languages are not programming languages. most people have some familiarity with some markup language.

The 60 year old math professors at my faculty read and wrote LaTeX perfectly fine. One time I helped find errors in the manuscript of a book one of my professors wrote in LaTeX by himself. He was 79 years old at that time